Panel comprising a locking system

ABSTRACT

The invention relates to a panel ( 1, 2 ) comprising a quadrangular panel portion of coated wood material wherein mutually opposite edges of the panel ( 1, 2 ) have mutually complementary positively locking profiles ( 3, 4 ) so that similar panels ( 1, 2 ) can be assembled, wherein the surface of at least one of the positively locking profiles ( 3, 4 ) has at least in region-wise manner raised portions ( 5, 6, 7 ) and recesses ( 8, 9 ), the raised portions ( 5, 6, 7 ) during assembly of two panels ( 1, 2 ) can be ground down by friction, and the recesses ( 8, 9 ) are of a volume in which resulting abrasion particles ( 5   a,    6   a,    7   a ) from the projections ( 5, 6, 7 ) can be received.

The invention relates to a panel comprising a quadrangular panel portionof coated wood material, wherein mutually opposite edges of the panelhave mutually complementary positively locking profiles so that similarpanels can be assembled.

Panels of the general kind set forth are used for example for theproduction of floor coverings, so-called laminate panels. Equally panelsof that kind can be designed in the form of wall or ceiling panels.Predominantly the panels comprise medium-density fibreboard (MDF) orhigh-density fibreboard (HDF), on to which further layers, mostlyresin-impregnated cellulose layers, are laminated. Frequently thepositively locking profiles are provided integrally on the panels, forexample by being milled thereon. In general terms the panels are of arectangular configuration with two long edges which are in mutuallyopposite relationship and two short edges which are in mutually oppositerelationship.

The thickness of the laminate panels is generally less than thethickness of parquet panels. Usual thicknesses are in a range of between5 and 8 mm. Thinner or thicker laminate panels are rare. It will benoted however that parquet panels have in the meantime also beenprovided with positively locking profiles. Therefore the positivelylocking profiles of the proposed new panel can also be provided onparquet panels.

The complementary positively locking profiles of the one panel arerestricted by the thickness of the panel and are fairly small. Theytherefore have to be produced very accurately in terms of shape and fitso that they fit one into the other. A high degree of fitting accuracyin respect of the complementary positively locking profiles is animportant requirement in order to ensure in particular a closed joint ona top side of the interlocked panels because the surface is visible tothe user of a finished floor covering. Particularly for floors it isdesirable to have a smooth surface in which the joints between thepanels do not form any gaps but the edges are in closely mutuallybutting relationship and are in contact with each other.

In the case of almost all panels with positively locking profiles, oneof the complementary positively locking profiles can be viewed as aninner portion and the associated profile can be viewed as an outerportion. The relationship of an outer portion to an associated innerportion prior to the portions being joined together is referred to asthe fit. Both the outer portion and also the inner portion involve givennominal dimensions, wherein tolerances are allowed for each nominaldimension. Each positively locking profile whose actual dimension iswithin the tolerance can be used. In accordance with a system fits aredivided into three different kinds: a clearance fit, an interference fitand a transition fit. The subdivision is always based on the dimensionalrelationship of the outer portion with its tolerance to the innerportion with its tolerance prior to joining of the two portions.

In the case of a clearance fit the tolerances even in the worst casescenario are such that at any event after joining there is a clearancebetween the outer portion and the inner portion.

In the case of an interference fit the tolerances are such that at anyevent after the joining operation there is an overdimension between theouter portion and the inner portion and there must therefore be elasticdeformation of the portions being joined.

The situation is referred to a transition fit if the tolerance rangeswhich are allowed for the outer portion and the inner portion partiallyoverlap. Without knowledge of the precise actual dimensions of the outerportion and the inner portion the combination of an outer portion whichis within its tolerance with an inner portion which is also within itstolerance, in the assembled condition, can give either a clearance or anoverdimension or in the ideal case an exact fit which has neitherclearance nor overdimension.

In order in the case of panels always to have a closed joint on the topside of the panels which is visible in the laid condition, it is knownfrom WO 97/47834 to provide on a positively locking profile elasticdeformation which produces prestressing of the panels. By means of thatprestressing, the panels are forced towards each other and in that waythe joint is held in a closed condition at the top side of the panels.The panel known from WO 97/47834 involves a modified tongue-and-groovepanel, wherein the tongue and the groove are each of an undercutconfiguration. The geometry of the positively locking profiles givesrise to elastic deformation at one of the groove walls, namely the lowergroove wall which in the laid condition is towards the surface on whichthe panel is laid. The deformed lower groove wall flexes like a beamwhich is gripped at one end. In the assembled condition of two panelsflexing of the groove wall is at least partially retained. The closednature of the joint is achieved by spring resiliency of the lower groovewall and by virtue of a particular geometry of the groove wall and thetongue, which involves the action of inclined surfaces which bearagainst each other.

There is the disadvantage in accordance with the teaching of WO 97/47834that the internal cohesion of the wood material is weakened by thepermanent flexing effect. The higher the degree of deformation, thecorrespondingly ‘softer’ becomes the wood material in the flexurallydeformed region. A further disadvantage is that, in the event of aloading applied over a long period of time, relaxation of the woodmaterial occurs in the flexurally deformed region. Absorption ofmoisture on the part of the wood material promotes the relaxationeffect, just like an action by heat. Admittedly, positively lockingprofiles of panels are usually impregnated with agents which areintended to prevent the absorption of moisture, but depending on therespective quality of the impregnation and the nature and location ofuse of the panel a gradual absorption of moisture cannot be prevented.

The object of the invention is to propose a panel whose positivelylocking profiles are of such a configuration that panels have closedjoints in the assembled condition without at the same time producingelastic deformation of a positively locking profile, such as to put astrain on wood material.

According to the invention that object is attained in that the surfaceof the positively locking profiles has at least in region-wise mannerraised portions and recesses, that the raised portions can be groundaway by friction during assembly of two panels, and that the recessesare of a volume in which resulting abrasion particles from the raisedportions can be received.

In the joining operation the raised portions are ground away to therequired dimension. A closed joint is formed at the top side of thepanel. In addition, a uniform heightwise level without heightwisedisplacement at the joint is achieved.

Due to the action of heat, the positively locking profiles can beincreased in size or they can swell up due to the action of moisture.Due to use in the specified manner, namely on a soft, footstepnoise-attenuating support, in those cases grinding of the raisedportions continues. That provides for renewed adaptation of the fittingshape of the positively locking profiles and accordingly affords asuitable fit without overdimension and without clearance.

Desirably, one of the positively locking profiles is in the form of agroove profile with an undercut configuration and the oppositelydisposed positively locking profile is in the form of a tongue profilewith an undercut configuration. The undercut configurations of thetongue profile and the groove profile can be fitted one into the otherby virtue of inclined positioning of the panels. Subsequent pivoting ofthe panels into a common plane locks them. The locking effect isoperative in the plane of the panels to prevent them from being pulledapart in a direction perpendicular to the positively locking profiles.During the laying operation, the usual procedure is for a panel to belaid flat on a laying surface and then a new panel is attached in aninclined position to the laid panel. Pivoting the new panel into thecommon plane is effected by lowering it on to the laying surface. Theundercut configurations of the groove profile and the tongue profileengage behind each other. In that way the panels are locked together.

If the effect of grinding away the raised portions by the joiningoperation is not sufficient, that is to say if too little material isground away by the joining movement of pivoting a fresh panel downwardlyinto the plane of the lying panel, the positively locking profiles areground together by a subsequent reciprocating pivotal movement untilfitting accuracy in respect of the groove profile and the tongue profileis achieved. For that purpose it is also helpful if the panels arepivotably connected together, that is to say if the tongue profile ismounted similarly to a connecting joint member in the groove profilewhich forms a kind of pivoting joint socket. In that way the panels canbe pivoted out of an angular position of 180° relative to each otherboth in the positive direction and also in the negative direction. Thepivotal mobility permits a particularly good reciprocating grindingmovement. Before the panels are definitively laid on the laying surface,they can be loosely assembled for example on a table to ascertain therequired degree of grinding so as to achieve fitting accuracy. Duringthe laying operation, fitting accuracy can be checked at the respectivefree end of the laid panel surface because it is there that theconnection of the positively locking profiles is visible from the side.It is possible to look closely to investigate whether deformation of thepositively locking profiles has occurred. For objective investigation asto whether the situation involves such deformation, it is possible forexample to take a measurement of the total thickness of the lockedpanels in the region of the connected positively locking profiles. Ifthe total thickness exceeds a predetermined limit dimension the grindingoperation has to be continued.

Preferably the raised portions and the recesses are provided on thetongue profile and the groove profile has a smooth surface. The smoothsurface of the groove profile is in contact with the raised portions ofthe tongue profile in the condition in which the panels are assembled inpositively locking relationship. Desirably the raised portions andrecesses are arranged at an underside of the tongue profile which istowards a surface on which the panels are laid. In that way the shape ofthe profile is adapted to the desired function. Because a panel isjoined by inclinedly attaching a tongue profile to the groove profile ofa panel lying on a laying surface, the construction makes use of thatjoining movement for grinding away and adapting the raised portions.Both in the case of the subject-matter of claim 1 and also in the caseof the development with raised portions and recesses at an underside ofthe tongue, adaptation of the fitting dimensions and the fitting shapeof the positively locking profiles takes place during the assemblyprocedure. In the condition prior to joining for example the positivelylocking profile with the raised portions has a ‘surplus’ of material. Inrelation to the complementary positively locking profile, there is anoverdimension prior to the joining procedure. During the joiningprocedure material is ground away from the raised portions and theoverdimension is removed. In that case the result is a connection inwhich there is neither an overdimension nor a clearance. Rather, thatprovides for exact adaptation of the positively locking profiles, whichensures a closed joint. The stiffness of the positively locking profilesas well as the abrasion resistance of the raised portions are desirablyso matched to each other that forces which occur during the assemblyoperation can admittedly provide for abrasion removal of the raisedportions, but not elastic deformation of the positively lockingprofiles.

The raised portions and recesses on the positively locking profile orprofiles can be in the form of a microstructure which is incorporatedinto the surface of the positively locking profiles.

A further advantage is afforded by a sealing and lubricating agent whichis provided at least in the recesses. Assembly of the panels by arotating joining movement is made easier by the lubricant effect.

In addition the raised portions on the positively locking profile can bebetter ground away by virtue of the wetting action, than in the drycondition. In the dry condition the raised portions can break off. Suchbreakage is prevented by the lubrication effect.

The grindability of the raised portions depends substantially on theshape thereof. A broad raised portion is less at risk of breaking offduring the assembly procedure than a narrow raised portion. In the caseof a narrow raised portion however there is desirably less materialwhich has to be ground away for the purposes of an accurate fit.Together with a lubricating agent, narrow raised portions have proven tobe desirable because simple adaptation is possible without the raisedportions breaking off.

The invention is illustrated by way of example hereinafter in a drawingand described in detail with reference to the Figures in which:

FIG. 1 shows a view of portions of complementary positively lockingprofiles of two panels prior to the joining operation,

FIG. 2 shows the beginning of a joining operation for the positivelylocking profiles of FIG. 1,

FIG. 3 shows a joining operation which is advanced in relation to FIG.2,

FIG. 4 shows a portion-wise enlargement of two locked positively lockingprofiles,

FIG. 5 shows two positively locking profiles in a hingedly pivotedcondition, and

FIG. 6 shows the positively locking profiles of FIG. 5 with lubricant.

FIG. 1 shows a view of a portion of two panels 1 and 2 comprising acoated panel portion of wood material. Each of the panels 1 and 2 has atmutually opposite sides positively locking profiles which are milledintegrally on the panel portion or portions. The positively lockingprofiles involve a groove profile 3 of an undercut configuration and atongue profile 4 of an undercut configuration. Each of the panels 1 and2 has a respective complementary profile at mutually opposite edges. Thepanel 1 is thus provided at the edge in opposite relationship to itsgroove profile 3 with a complementary tongue profile and equally thepanel 2 with the tongue profile 4 is provided at the edge opposite tothe tongue profile 4 with a complementary groove profile. The panels 1and 2 are rectangular. These kind of complementary profiles are alsoprovided for the other two edges of the panels. The positively lockingprofiles 3 and 4 are shown in FIG. 1, prior to being joined. The panel 1is disposed on a laying surface V. The panels are coated. A decorativecoating comprising a plurality of layers is arranged at a top side A ofeach of the panels, being the side which is away from the laying surfaceV in the laid condition. An underside B which is in oppositerelationship to the top side is provided with a counteraction layer.

The tongue profile 4 of the panel 2 has a tongue underside 4 a withraised portions 5, 6 and 7 and recesses 8 and 9. The tongue underside 4a faces towards the laying surface V in the assembled condition of thepanels 1 and 2. The groove profile 3 of the panel 1, towards the layingsurface V, has a lower groove wall 10 and an upper groove wall 11. Thelower groove wall 10 has a channel-shaped receiving means 10 a on itsinward side. The channel-shaped receiving means 10 a receives the tongueunderside 4 a of the panel 1 in the assembled condition.

The channel-shaped receiving means 10 a is provided with a concavelycurved surface which is without raised portions and recesses. Thecomplementary configuration of the positively locking profiles relatesto the basic shapes of the groove profile 3 as an outer portion and thetongue profile 4 as an inner portion which fit one into the other. Theraised portions 5, 6 and 7 and the recesses 8 and 9 at the tongueunderside 4 a are not in the form of a negative shape in thechannel-shaped receiving means 10 a of the groove profile. In spite ofthose differences between the positively locking profiles 3 and 4, theyare referred to in accordance with the invention as complementarypositively locking profiles.

The free end of the groove wall 10 projects from the edge of the panel 1further than the upper groove wall 11. The free end of the upper groovewall 11 projects from the edge of the panel approximately as far as thelowest point of the channel-shaped receiving means 10 a. The lowestpoint of the channel-shaped receiving means 10 a is that point which isat the smallest spacing relative to the underside B of the panel 1,perpendicularly to the plane of the panel. On its inside the uppergroove wall 11 has a bevel 11 a. The bevel means that the thickness ofthe upper groove wall decreases from the free end thereof towards thebottom of the groove 3.

Prior to the operation of joining the positively locking profiles 3 and4 the raised portions 5, 6 and 7 shown in FIG. 1 at the tongue underside4 a of the tongue profile 4 involve an overdimension in relation to theshape and dimensions of the groove profile 3.

In the assembled condition, the connection of the tongue profile 4 tothe groove profile 3 of the panel 1 forms a hinge joint G. The hingejoint G permits an angular movement of the panels 1 and 2 relative toeach other. In a basic position the panels 1 and 2 are at an angle of180° relative to each other. The panels 1 and 2 can be pivoted out ofthat basic position both into a position involving an angle of greaterthan 180° relative to each other and also into a position involving anangle of less than 180°. A position of the panels 1 and 2 at an angle ofgreater than 180° relative to each other is described hereinafter withreference to FIG. 5.

FIG. 2 shows how the positively locking profiles are joined together byengaging one into the other. A panel 1 is lying on the laying surface 4and is disposed with its groove profile 3 facing towards a new panel 2.The new panel 2 is inserted with its tongue profile 4 into the grooveprofile 3 of the lying panel 1, in which case the new panel 2 is set inan inclined position or is angled with respect to the lying panel 1. Asillustrated a first raised portion 5 of the tongue underside 4 a of thepanel 2 comes into contact with the lower groove wall 10 of the grooveprofile 3. When that happens the tip of the raised portion 5 rubsagainst the surface of the channel-shaped receiving means 10 a and isground away thereat. Abrasion particles 5 a which are produced pass intothe recess 8 and are entrained therein during the further joiningmovement.

FIG. 3 shows the joining operation in a further stage. A second raisedportion 6 has come into contact with the surface of the channel-shapedrecess 10 a and is ground away thereat. Abrasion particles 6 a which areproduced are stored in the recess 9 which is arranged behind the secondrecess 6 in the joining direction of the tongue profile 4. In that waythe shape of the tongue profile 4 is adapted to the shape of the grooveprofile 3 during the assembly procedure.

The finished assembled condition of the positively locking profiles 3and 4 is shown in FIG. 4. In that case a third raised portion 7 has alsocome into contact with the surface of the channel-shaped recess 10 a ofthe groove wall 10 and has been ground away thereat. Abrasion particles7 a which are produced in that situation are disposed in an intermediatespace between the lower groove wall 10 of the groove profile 3 and thetongue profile 4. A closed joint F is produced at the top side A of thepanels, which is away from the laying surface V. The joint F is formedby an end face 11 b of the upper groove wall 11 of the groove profile 3and by a contact face 12 which is provided on the tongue profile 4 andwhich extends from the tongue top side 4 b to the surface of the panel2. In that condition the end face 11 b bears without pressure againstthe contact face 12. The inner portion—tongue profile 4—of the panel 2fits without clearance into the outer portion—groove profile 3—of theadjacent panel 1. Elastic deformation which strains the positivelylocking profile does not occur.

The particularity of the structure is that the relationship of thefitting shapes of the positively locking profiles to be joined changesduring the assembly procedure. In the present embodiment the fittingshape of the tongue profile 4 is matched to that of the groove profile3. Alternatively however it is also possible for the groove profile tobe provided with raised portions and recesses which grind each otheraway. It is immaterial in terms of the function of the connection, atwhat location adaptation takes place by virtue of material being groundaway. The number of raised portions is not fixed at three. It ispossible for example to provide a microstructure comprising a pluralityof raised portions which are substantially smaller than those of thedescribed embodiment.

Prior to the joining operation there is a ‘surplus’ of material in theregion of the raised portions 5, 6 and 7 of the tongue profile 4. Thatoverdimension is ground away during the assembly procedure for thepositively locking profiles until the fitting shape of the inner portionis adapted to that of the outer portion.

For that purpose the stiffness of the positively locking profiles 3 and4 and the abrasion resistance of the raised portions 5, 6 and 7 are somatched to each other that forces which occur during the assemblyprocedure can admittedly cause the raised portions 5, 6 and 7 to berubbed away, but they cannot give rise to elastic deformation of thepositively locking profiles 3 and 4 respectively.

If the degree to which the raised portions 5, 6 and 7 are ground away bythe joining operation is not sufficient, that is to say, if too littlematerial is ground away by the joining movement involving pivotalmovement of the panel 2 down into the plane of the lying panel 1, thenthe positively locking profiles 3 and 4 must be ground in against eachother until fitting accuracy is achieved, by a subsequent reciprocatingpivotal movement. For that purpose it is extremely helpful if the panels1 and 2 are hingedly connected and can be pivoted from an angularposition of 180° relative to each other both in the positive directionand also in the negative direction. The pivot joint G and the mobilitythereof are indicated in FIG. 5 in which the panels 1 and 2 are at anangle relative to each other which is larger than 180°. That permits aparticularly good reciprocating grinding movement. Prior to the panels 1and 2 being definitively laid on the laying surface V, they can be forexample loosely assembled on a table in order to ascertain the extent towhich they have to be ground in against each other so as to achievefitting accuracy. During the laying operation, fitting accuracy can bechecked at the respective free end of the locked panel surface. There,the connection between the positively locking profiles 3 and 4 isvisible from the side. It is possible to examine the arrangement toascertain whether deformation of the positively locking profiles 3 and 4has occurred. For the purpose of objectively checking whetherdeformation is present, it is possible for example to take a measurementof the total thickness of the panels 1 and 2 in the region of the joinedpositively locking profiles 3 and 4. If the total thickness exceeds apredetermined limit dimension the grinding-in operation has to becontinued.

FIG. 6 shows an embodiment of panels 1 and 2 whose positively lockingprofiles 3 and 4 are treated with a so-called insulating wax. Thisinvolves an agent which provides lubrication for the joining movement ofthe positively locking profiles 3 and 4. In addition the insulating waxis squeezed into free intermediate spaces 13 a, 13 b and 13 c within thelocked positively locking profiles 3 and 4 and is pressed for example inthe form of a thin film into the joint F at the top side of the panels 1and 2. In that way the insulating wax acts as a sealing agent. Thesealing agent is applied in an amount which at least partially coversthe surface of the positively locking profiles. That prevents theingress of moisture into the joint F and thus into the wood material.Otherwise the wood material would swell due to the absorption ofmoisture. The amount of insulating wax can fill up the intermediatespaces 13 a, 13 b and 13 c or can be of a somewhat smaller quantity sothat free spaces remain. In addition its lubricating property providesthat creaking or grating noises do not occur in the region of thepositively locking profiles 3 and 4 of the panels 1 and 2 because alubricant film is formed. Creaking or grating noises occur in the caseof panels 1 and 2 when a relative movement takes place between thepositively locking profiles 3 and 4. That is the case for example whenlaying floor panels on a flexible, footstep sound-damping support,because the panels 1 and 2 sink into the flexible support when loaded atthe connecting location.

LIST OF REFERENCES

-   1 panel-   2 panel-   3 groove profile-   4 tongue profile-   4 a tongue underside-   4 b tongue top side-   5 raised portion-   5 a abrasion particle-   6 raised portion-   6 a abrasion particle-   7 raised portion-   7 a abrasion particle-   8 recess-   9 recess-   10 groove wall-   10 a channel-shaped recess-   11 groove wall-   11 a bevel-   11 b end face-   12 contact face-   13 a intermediate space-   13 b intermediate space-   13 c intermediate space-   A top side-   B underside-   F joint-   G pivot joint-   V laying surface

1-7. (canceled)
 8. A panel comprising a quadrangular panel portion ofcoated wood material, wherein mutually opposite edges of the panel havemutually complementary positively locking profiles so that similarpanels can be assembled, and wherein the surface of at least one of thepositively locking profiles has at least in region-wise manner raisedportions and recesses, characterized in that the raised portions areprovided with an overdimension, that the overdimension can be groundaway by friction during assembly of two panels, and that the recessesare of a volume in which resulting abrasion particles from the raisedportions can be received.
 9. The panel according to claim 8characterized in that the positively locking profile is in the form of agroove profile with an undercut configuration and the oppositelydisposed positively locking profile is in the form of a tongue profilewith an undercut configuration.
 10. The panel according to claim 9characterized in that the raised portions and recesses are provided onthe tongue profile and the groove profile has a smooth surface which isin contact with the raised portions in the positively lockinglyassembled condition.
 11. The panel according to claim 10 characterizedin that the raised portions and recesses are arranged at a tongueunderside which faces towards a laying surface.
 12. The panel accordingto claim 8 characterized in that the stiffness of the positively lockingprofiles and the abrasion resistance of the raised portions are somatched to each other that forces which occur during the assemblyprocedure can cause the raised portions to be rubbed away but cannotcause elastic deformation of the positively locking profiles.
 13. Thepanel according to claim 8 characterized in that there is provided asealing and lubricating agent at least in the recesses.
 14. The panelaccording to claim 13 characterized in that the sealing and lubricatingagent forms a lubricating film.